As can be seen in the chart above, earthquakes tend to fall around natural fault lines where tectnoic plates meet. Additionally, There appear to be significantly more lower magnitude earthquakes than higher magnitude earthquakes. This trend of more lower magnitude Earthquakes holds for any selected part of the world.

The number of lower magnitude earthquakes appears to increase a lot around 1970, possibly leading to the conclusion that lower magnitude earthquakes simply became more common then. However, what really changed was our ability to measure lower magnitude earthquakes. With the rise of seismology and earthquake related studies, 1972 marked the year when lower magnitude earthquakes became easier to detect. Thus, the increase in the number of low magnitude earthquakes in the 1970's is due to technological advances.